Volvo Ocean Race: The not so great circle route to Auckland
by Richard Gladwell, Sail-World.com/nz 23 Feb 2018 21:26 AEDT
23 February 2018
Leg 6 to Auckland, day 17 on board MAPFRE, Passing next to a reef of New Caledonia. 23 February, © Ugo Fonolla / Volvo Ocean Race
The six strong Volvo Ocean Race should now be clear of the light winds that have beset the fleet since they entered the Doldrums six days ago.
Now, Day 16 of Leg 6 they are on the final lap to Auckland, and interestingly all four feeds used for weather routing by Predictwind are in close agreement.
Well, they are in close agreement as to the route to take take but not in the time taken to finish in Auckland.
Only two feeds are allowed to be used on the boats and they are both supplied via Volvo Ocean Race. Despite recommending the same route they are telling quite a different story as to the arrival times with there currently being a 22 hour difference.
GFS is the more optimistic of the two, calculating and estimated arrival time of just after midnight on February 27 UTC, which is early afternoon local time in New Zealand. The other feed, the more accurate ECMWF, shows a finish time at 1927hrs UTC on February 27, that translates to a finish when Kiwis are heading for work on the morning of the February 28, or maybe earlier at 0630 local time.
The speeds are steady but not spectacular with the boats expected to average 17kts according to one feed (GFS) and 14kts according to ECMFS.
On current finish time projections, and provided the weather data stays consistent with the cuurent projections, Team AkzoNobel will beat SHK Scallywag into Auckland by one and a half hours based on one projection and four hours on the other.
The rider with any radical course deviation from the accepted Great Circle route is that there is always the risk that the trailing boats will take a leaf out of SHK Scallywag's navigation playbook, and cut the corner - chancing their luck on the accepted Great Circle route.
If the navigators could see the other two feeds used in Predictwind they would know that they were a lot closer to ECMWF, in terms of time expected to be taken, and obviously in the course shape which sees the leaders sailing a big semi-circle to get to Auckland.
At the 0700hrs UTC sched on February 23, the leaders were well past the northern cape of New Caledonia and were sailing down its western side looking to make a rendezvous with an area of stronger wind coming out of the SW western corner of the Tasman Sea which will give the fleet a fast and steady ride into Auckland.